VAX 11/750 power supply fault

[cctech at vax-11.org]

On Sat, 1 Dec 2007, J Blaser wrote:

> Quoting Dave McGuire <mcguire at neurotica.com>:
>
>> On Nov 30, 2007, at 10:30 PM, J Blaser wrote:
>>> cheekiness, does anyone have schematics and/or Engineering Drawings
>>> for this 11/
>>> 750.  Maybe I could actually try to sort it out if I had some more
>>> information,
>>> at least until I electrocute myself!  :o
>>
>>    I'm fairly certain that I have 11/750 prints here, but I will have to
>> find them.  Let me know if you don't find them elsewhere quickly enough
>> and I'll start digging.
>
> Thanks, Dave, for the offer (and to all others giving helpful advice in this
> thread).  I *did* find the schematics last night on vt100.net/manx, so I just
> need to spend some time now looking them over, and seeing what I can do.
>
> I do have some very basic tools, and a 'scope, and I guess my plan is to try to
> look for some bad passives first, unpowered, then take whatever next steps seem
> reasonable.  These PSs are pretty tightly packed, in a 3-D kind of way, and I'm
> not sure I'm up to poking around inside with it powered.  I might touch
> something I shouldn't with a probe, and make things worse! ;)  We will see...
>
> As things progress I'll give a report, but don't hold your breath for quick
> news.  I've got a lot to learn first.
>
> Thanks.
>
> - Jared
>

I like to solder wires to interesting points, run them outside of 
whatever I'm working and attach them to a something (paint stir stick) 
so they don't short out. That way I can look at the signals without 
risking a short, especially on high voltage stuff.

Clint